1. To put aside, to abandon, or to change or exchange: Mildred decided to switch her plans to go shopping today and so she will go tomorrow instead.
2. To move quickly: When an animal switches its tail, it moves fast and suddenly, back and forth, from side to side.
3. To cause an electric current or an appliance to start or stop operating: Roy switched the lights on earlier in the evening, then he switched them off when he was ready to go to bed.